The common reasons for the left side of the stomach beating like a heartbeat are as follows: 1. Large blood vessel beating: such cases may be caused by large blood vessel beating, such as the abdominal aorta is in the middle of the navel slightly to the left, if the patient has a thin body type and less fat in the abdominal wall, the beating can be observed. Therefore, if the patient has a rhythmic heartbeat, it may be an abdominal aortic beating; 2. Vascular lesions: If the patient feels a more pronounced beating, he or she needs to be alert to abdominal aortic aneurysm. Abdominal aortic aneurysm is not a real tumor, but a spherical lumen formed by the outward protrusion of the abdominal aorta. However, blood from the abdominal aorta fills the cavity and drains outward with the heartbeat, resulting in a pulsating beating sensation. Such patients need to be seen in vascular surgery or cardiac macrovascular surgery to identify vascular lesions and hemangiomas through enhanced CT of the abdomen and then treated accordingly. If there is no lesion, the patient can be assured that the beating is a normal beating of the abdominal aorta and no special treatment is needed.